1 // SPDX-License-Identifier: GPL-2.0
2 /*
3 * Memory preserving reboot related code.
4 *
5 * Created by: Hariprasad Nellitheertha (hari@in.ibm.com)
6 * Copyright (C) IBM Corporation, 2004. All rights reserved
7 */
8
9 #include <linux/errno.h>
10 #include <linux/crash_dump.h>
11 #include <linux/uaccess.h>
12 #include <linux/io.h>
13 #include <linux/cc_platform.h>
14
__copy_oldmem_page(unsigned long pfn,char * buf,size_t csize,unsigned long offset,int userbuf,bool encrypted)15 static ssize_t __copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
16 unsigned long offset, int userbuf,
17 bool encrypted)
18 {
19 void *vaddr;
20
21 if (!csize)
22 return 0;
23
24 if (encrypted)
25 vaddr = (__force void *)ioremap_encrypted(pfn << PAGE_SHIFT, PAGE_SIZE);
26 else
27 vaddr = (__force void *)ioremap_cache(pfn << PAGE_SHIFT, PAGE_SIZE);
28
29 if (!vaddr)
30 return -ENOMEM;
31
32 if (userbuf) {
33 if (copy_to_user((void __user *)buf, vaddr + offset, csize)) {
34 iounmap((void __iomem *)vaddr);
35 return -EFAULT;
36 }
37 } else
38 memcpy(buf, vaddr + offset, csize);
39
40 set_iounmap_nonlazy();
41 iounmap((void __iomem *)vaddr);
42 return csize;
43 }
44
45 /**
46 * copy_oldmem_page - copy one page of memory
47 * @pfn: page frame number to be copied
48 * @buf: target memory address for the copy; this can be in kernel address
49 * space or user address space (see @userbuf)
50 * @csize: number of bytes to copy
51 * @offset: offset in bytes into the page (based on pfn) to begin the copy
52 * @userbuf: if set, @buf is in user address space, use copy_to_user(),
53 * otherwise @buf is in kernel address space, use memcpy().
54 *
55 * Copy a page from the old kernel's memory. For this page, there is no pte
56 * mapped in the current kernel. We stitch up a pte, similar to kmap_atomic.
57 */
copy_oldmem_page(unsigned long pfn,char * buf,size_t csize,unsigned long offset,int userbuf)58 ssize_t copy_oldmem_page(unsigned long pfn, char *buf, size_t csize,
59 unsigned long offset, int userbuf)
60 {
61 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, false);
62 }
63
64 /**
65 * copy_oldmem_page_encrypted - same as copy_oldmem_page() above but ioremap the
66 * memory with the encryption mask set to accommodate kdump on SME-enabled
67 * machines.
68 */
copy_oldmem_page_encrypted(unsigned long pfn,char * buf,size_t csize,unsigned long offset,int userbuf)69 ssize_t copy_oldmem_page_encrypted(unsigned long pfn, char *buf, size_t csize,
70 unsigned long offset, int userbuf)
71 {
72 return __copy_oldmem_page(pfn, buf, csize, offset, userbuf, true);
73 }
74
elfcorehdr_read(char * buf,size_t count,u64 * ppos)75 ssize_t elfcorehdr_read(char *buf, size_t count, u64 *ppos)
76 {
77 return read_from_oldmem(buf, count, ppos, 0,
78 cc_platform_has(CC_ATTR_GUEST_MEM_ENCRYPT));
79 }
80